@@ -1364,6 +1364,7 @@ static void __init filter_events(struct attribute **attrs)
{
struct device_attribute *d;
struct perf_pmu_events_attr *pmu_attr;
+ int offset = 0;
int i, j;
for (i = 0; attrs[i]; i++) {
@@ -1372,7 +1373,7 @@ static void __init filter_events(struct attribute **attrs)
/* str trumps id */
if (pmu_attr->event_str)
continue;
- if (x86_pmu.event_map(i))
+ if (x86_pmu.event_map(i + offset))
continue;
for (j = i; attrs[j]; j++)
@@ -1380,6 +1381,14 @@ static void __init filter_events(struct attribute **attrs)
/* Check the shifted attr. */
i--;
+
+ /*
+ * event_map() is index based, the attrs array is organized
+ * by increasing event index. If we shift the events, then
+ * we need to compensate for the event_map(), otherwise
+ * we are looking up the wrong event in the map
+ */
+ offset++;
}
}
This is a note to let you know that I have just added a patch titled perf/x86: Fix filter_events() bug with event mappings to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt34. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 3de75b15d92800380c2784973fe975172b2fe503 Mon Sep 17 00:00:00 2001 From: Stephane Eranian <eranian@google.com> Date: Mon, 7 Dec 2015 20:33:25 +0100 Subject: perf/x86: Fix filter_events() bug with event mappings commit 61b87cae6361ea6af161c1ffa549898892707b19 upstream. This patch fixes a bug in the filter_events() function. The patch fixes the bug whereby if some mappings did not exist, e.g., STALLED_CYCLES_FRONTEND, then any event after it in the attrs array would disappear from the published list of events in /sys/devices/cpu/events. This could be verified easily on any system post SNB (which do not publish STALLED_CYCLES_FRONTEND): $ ./perf stat -e cycles,ref-cycles true Performance counter stats for 'true': 1,217,348 cycles <not supported> ref-cycles The problem is that in filter_events() there is an assumption that the argument (attrs) is organized in increasing continuous event indexes related to the event_map(). But if we remove the non-supported events by shifing the position in the array, then the lookup x86_pmu.event_map() needs to compensate for it, otherwise we are looking up the wrong index. This patch corrects this problem by compensating for the deleted events and with that ref-cycles reappears (here shown on Haswell): $ perf stat -e ref-cycles,cycles true Performance counter stats for 'true': 4,525,910 ref-cycles 1,064,920 cycles 0.002943888 seconds time elapsed Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: jolsa@kernel.org Cc: kan.liang@intel.com Fixes: 8300daa26755 ("perf/x86: Filter out undefined events from sysfs events attribute") Link: http://lkml.kernel.org/r/1449516805-6637-1-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/x86/kernel/cpu/perf_event.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) -- 1.9.1